Sporadic

Isolated cases of lab-confirmed influenza in the state; ILI activity not increased.

     OR

Lab-confirmed outbreak in a single institution in the state; ILI activity is not increased.

Local outbreak

Increased ILI within a single region AND recent (within the past 3 weeks) laboratory evidence of influenza in that region. ILI activity in other regions is not increased.

     OR

Two or more institutional outbreaks (ILI or lab-confirmed) within a single region AND recent lab-confirmed influenza in that region. Other regions do not have increased ILI and virus activity is no greater than sporadic in those regions.

Regional

Increased ILI in at least 2 but less than half of the regions AND recent lab-confirmed influenza in the affected regions.

     OR

Institutional outbreaks (ILI or lab-confirmed) in more than 2 and less than half of the regions AND recent lab-confirmed influenza in the affected regions.

Widespread

Increased ILI and/or institutional outbreaks (ILI or lab-confirmed) in at least half of the regions AND recent lab-confirmed influenza in the state.